


What If #1: What if Dedue Molinaro were a merman?

by queenowl



Series: What If? [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe, Alternate Universe - Fantasy, Drama, F/M, Fantasy, Mermen AU, Romance
Language: English
Status: Completed
Published: 2019-10-22
Updated: 2019-10-22
Packaged: 2020-12-28 13:39:45
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,640
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21137597
Author URL: https://archiveofourown.org/users/queenowl/pseuds/queenowl
Summary: Byleth is what her father calls a "magnet for mystery", someone who pulls trouble towards her at every turn. One of those "mysteries" she attracts is a young boy from the waves with a fishtail instead of legs. Little does she know what this fateful encounter will mean for her more than ten years later, when she's become a professor at Garreg Mach's Officer's Academy...





	What If #1: What if Dedue Molinaro were a merman?

**Author's Note:**

> This is a new series! Welcome! It's not going only be Bydue but... of course the first one is going to be Bydue because I'm predictable.
> 
> I admit AUs are kind of my weak point but I still like to challenge myself... anyway, excuse me in advance if you hate it or find it super OOC. o7;; I tried my best!

The first time they meet, he is on the brink of death.  
  
Byleth is a small child of ten, feet bare as she walks along the sands and sees the gasping form for the first time. Her father normally worries when she wanders at night especially, but she cannot help her drawn to the sea by the most recent home they have made, a small hut by the sea in a sea-trading village that could not be further from the halls of Garreg Mach. Particularly, from the Archbishop of Garreg Mach, who he is still certain had a hand in his wife's death.  
  
This night is no different.  
  
She draws closer with wide eyes only to see that it is not... not an 'it' at all. A boy her age, or slightly younger, lies there, his dark skin shimmering with scales around his eyes and ears and chest. In one ear, she can see it: a heavy, golden earring in a single ear. It is not very large and yet it feels as though it weighs more than his exhausted frame can bear. His eyes roam wildly and, when they catch sight of her for the first time, there is no fear in them. Instead, they gaze at each other with looks that do not suit their ages; his eyes are too serious and hers too wise for forms so young.  
  
Neither of them speak as her eyes catch sight of the space below his hips, a glittering thick tail that reminds of her the largest fish she has never seen. It flops uselessly against the sand. He points to the ocean, still gasping slightly. For a moment, she thinks to grasp his tail, but he is much too slippery and her grip is too small to be effective. Holding up a hand, Byleth nods with determination, running back to her home.  
  
The child's eyes trail after her, his tail flopping weakly against the sands as he gasps for breath.  
  
"Father. There is a fish boy here." Her deadpan voice rouses him, little hands shaking his solid form with as much haste as she can muster. "We must help him." Jeralt forces his eyes to open. He has long since accepted that his child's quirks are ones that he perhaps will never be able to understand and so, when he sees her tugging his sleeves, urgently motioning towards the door, he merely sighs and forces himself to sit up. _Fish boy? _He follows her outside of the house where the child still lies, breath weaker than before.  
  
_Okay, then. A... a fish boy it is._  
  
He grimaces slightly at the continued mysteries of the world. In reality, Jeralt does not care so much that they exist--but he is more or less fed up with the idea that these mysteries choose to find themselves on his particular doorstep. Taking no time to waste, he hoists the child wholesale into his arms, hastening towards the ocean to dip him inside. At first, the boy sinks and he fears him dead, but then, his eyes burst open. Unlike the dull color they were on land, he can see them glowing in the night. With a flick of his tail, he disappears. Jeralt turns towards Byleth's wide-eyed form on the beach.  
  
"Hey, kid. Looks like your, uh, fish boy's going to be alright." He steps back onto the beach barefoot and scoops her into his arms. At ten, she is much too big to be held like this, but he's strong enough to do it anyway, and no one will tell him that his kid isn't his kid until she does so herself. She nods, then hugs him around the neck tightly as a thank you. "And what were you doing out so late anyway?" She blinks at him owlishly. "Ah, don't look at me like that... I know you're not going to say anything even if I ask, but you shouldn't be wandering around at night, kid. It's not safe." Jeralt sighs, shaking his head. "Come on, let's get you back to bed. We've got sword training in the morning."  
  
Byleth does not mention the child again, but Jeralt catches her, every once and a while, staring out towards the waves with some interest. The following weeks are uneventful, until the day Jeralt opens the door to a startling sight. An arrow entirely made of polished coral is driven deeply into his front door, a small pouch hanging front the shaft. He pulls it out, grunting with the effort. "Coral, huh..." He has an inkling of the arrow's origin. Opening the attached pouch, he checks it for anything dangerous.  
  
All in all, the assortment of items is benign: some flat polished stones, a small, golden fan shaped earring, or if he squinted, he guessed he could say it was shell-shaped... and besides that, a small, carved figurine that was unmistakably supposed to be of Byleth, also made of polished coral. He almost missed the tightly rolled scroll of seaweed-like paper, but when he unties and unravels it, there are scribbles that he could not begin to decipher.  
  
Sensing a presence close by, he notes Byleth's silent silhouette in the doorway.  
  
"No need to hide. It seems your fishy friend left you a little gift." He shakes his head, placing the pouch in her hands. Staring down at it in wonder, Byleth runs back into the house, then returns with something new cupped in her hands.  
  
"A flower? What, you want to give it back to him?" She nods solemnly. "Well, I'd hate to break it to you, kid, but I'm not sure it'll last for very long in the water." To his great chagrin, her expression falls. He struggles not to embrace her. _Ah, Jeralt, you're getting soft._ "Look, maybe if we make a flower out of something sturdier, he'll be able to receive it. How's that sound?" She nods, her expression blank, but the speed with which she does it expressing her enthusiasm clearly enough. Jeralt shakes his head as he motions behind him. "Let's go find some wood to work with first." Pausing, he places his hand on his child's head, gruff wonder in his voice. "I have to say, kid... You're a magnet for mystery."  
  
  
  
  
  
Byleth does not often think of her father's words when she dreams, but when she awakens that night, they are on her mind. She stares up at a ceiling of solid sturdy wood and not stars, and for a moment does not know who or what or where she is. Byleth reminds herself slowly as is her daily routine. She is no longer a mercenary. Now, she is a professor. _"A magnet for mystery..."_ She murmurs the phrase quietly to herself as she looks at the coral figurine on her dresser. She has never been one for reminiscing, so why this particular memory comes to mind and rouses her is something that she cannot quite puzzle out.  
  
_"Yes, I agree."_ Sothis' voice rings out, despite her form choosing not to manifest. _"Something in your blood calls to the hidden beasts of this world, I think. How strange that I, too, remember that encounter."_ Sothis pauses thoughtfully. _"I wonder if my presence has something to do with it."_  
  
Byleth sighs. She just wants to sleep.  
  
_"No need to get huffy. Why don't you follow those magnetic instincts of yours, then? Something is surely calling you, and now I too am curious."_  
  
**Fine.**  
  
Frustrated, Byleth pulls on her cloak and quietly steps outside of her doors. She mutters under her breath. "Any ideas as to where my gut is pulling me?"  
  
Sothis is silent. Of _course_ she is. But perhaps she is answering in her own way, because, as Byleth's eyes trails the monastery, she finds herself knowing where to go. Her feet guide her towards the greenhouse, and further still, to the pier.

Coughing, choking, shuddering, she sees him dragging himself from beneath the water. Byleth looks around but there is no one on the grounds but her. Somehow, no one else is seeing what she is: a half-drowned stranger, wearing absolutely nothing at all as he drags himself from the depths pond onto the dry cobblestone, seagrass drapped across his ankles. She does not know why she does not sound an alarm--perhaps those instincts Sothis spoke of? Instead, she finds her legs hastening towards the figure.

"Are you--" Before she can speak further, he glares at her harshly, but she does not let the expression intimidate her, even as she can see a familiar glittering across his face. Scales...? Just like the fish b--her eyes shift sharply towards his bottom half before whipping back towards his face. _That_... is not a tail. Perhaps she... she is mistaken. She finishes her sentence more or less calmly, quickly removing her cloak and holding it out with a hand. "--alright?"  
  
He opens his mouth to speak, his lips moving quickly, but no sound comes forth. Alarmed, he touches his throat.  
  
_"So he cannot speak."_ Sothis' voice muses in her mind, mildly surprised. _"How unusual... and interesting. Take him to your room. Let me see if there is something I can do for the poor child."_

_Child?_

Byleth lifts an eyebrow at the word. He is the tallest man she has ever seen, bar none, with broad shoulders, high, chiseled cheek bones and wet silvery hair that glistens in the light of the full moon far above. She would hardly call him a child... Still, Byleth nods at the instruction and beckons with her hands. "Follow me." He struggles to stand, his knees collapsing as he supports his weight on shaking calves.  
  
Sothis makes her presence known then--not that he can see her. She floats about the man, observing him. _"Trouble walking as well? Perhaps this is not his usual form. If not, I completely understand what it is to wake up in the wrong body."_ She looks at him sympathetically, then gapes at Byleth. _"What, will you stand there, eying his flesh like a love-struck fool? Help him up!"_  
  
_Ah... right._ She quickly, clinically wraps the cloak around his waist and tosses an arm over her shoulders, grunting under his weight. Together, shakily, they hasten back to her room. Byleth seats him on her bed. First, she must find him clothes.  
  
"Wait here." Byleth has no clue if he can understand her, but she departs immediately for the one person she can trust to keep this a secret.  
  
He opens the door, takes one look at her steady stare and sighs. "Whatever it is, I have a feeling I'm not going to like this one bit." She steps inside the Captain's room and shuts it behind her.  
  
"Do you remember the fishboy?"  
  
Jeralt lifts an eyebrow. "I'm surprised that you do. Though, I guess, you did keep those little mementos he sent you over the years. Including your little earring there." Byleth touches the shell shaped piece dangling from her ear unconsciously, as though she is only just now remembering its origins. "I also remember having to shoot barrels of arrows into the ocean with your little gifts back. People must've thought I looked nuts wasting good shafts like that." He rubs his neck uncomfortably. "When we had to move on to the next town, I _also_ remember you were mad at me for two weeks. Didn't speak a word to me the entire time." _That happened?_ Byleth stares at him blankly. She only remembers their meeting, the gifts and... well. Not much else. Her eyes trail towards the ground with something like guilt, but Jeralt grins. "Oh, don't feel _too_ bad. Your old man's heart's recovered by now." He sobers up. "Now. What is it you want to tell me?"  
  
"I need your clothes."  
  
"_My_ clothes? Why would you..." Jeralt trails off. "Is he... is he here? Or someone like him?" Byleth shrugs in reply and Jeralt can tell that's all he's getting out of her. He shakes his head. "Never mind. I'm better off not knowing, anyway." He shuffles through his drawers and hands her a set of linen clothes. "Whatever you do with them, I don't need to know. You don't even need to give them back. Just... look. If there's one thing I've learned about raising you, it's that you're someone who attracts all kinds of trouble. Be safe, alright?" Byleth nods solemnly, taking the clothes. "Alright. See you, kid."  
  


  
When she returns to the room, the massive man is still seated on her bed, her cloak wrapped around his waist like a towel. He is staring down at something clasped in hands. She looks to see what he's holding when--a look of displeasure flashes across her face.  
  
"Don't touch that!" He looks up, startled for a moment before his expression relaxes. Slowly, deliberately, he places it back onto the table, lifting his hands in an apology. Byleth places the table on the other end, then picks up the figurine to inspect it carefully. As she does, she suddenly feels his presence behind her. She turns and he is close. Her eyes widen as he closes his hand around the one holding the figurine carefully.  
  
Pointing to himself, he shakes her hand lightly. She pulls away, uncomprehendingly, but her back only hits the table. He doesn't move closer, a look of passive acceptance crossing his face. He backs away, taking a seat back onto the bed.  
  
_"He's trying to tell you something! What could it possibly be?"_ There is sarcasm in Sothis's voice that Byleth ignores.  
  
**I'll ask him once he's fully clothed**, is her dry, inward retort. Sothis huffs.  
  
_"Clothed? As if such a thing would bother me."_  
  
**Exactly. Bother _you_. But I'm human, and he's...** She lets the thought trail off. _Is_ she human? Maybe? But... she looks over her shoulder as he broods silently, staring at the ground. His chest and arms are still glittering slightly, but if she isn't mistaken, the scales seems to have... retreated? They are certainly less evident than they were before.  
  
Byleth turns back the clothes on the table. _First to make good on her promise._ "Hey." He looks up. Byleth starts with the smallclothes and pants, and miming stepping into them, she hands them to him before turning her back.  
  
Sothis chuckles lightly into her ear. _"I think I have a proposal."_  
  
She tries not to sigh aloud in reply. **...Proposal?**  
  
_"I need you to touch him on the chest. If I can touch his heart, perhaps I can lend him some of my power."_ Byleth feels her face heating up, her eyes narrowing.  
  
**You wish for me to lay hands on a stranger?**  
  
_"As if such a thing would bother you. I can read your thoughts, even those you dismiss, and I know exactly what you thought when you saw his--"_  
  
**Stop! Please stop speaking.**  
  
_"Tsk! So impudent! But, as you wish. Besides, I was going to say... I don't think he's as much of a stranger as you think."_  
  
**What does that mean?**  
  
_"Oh, as if you do not know. You called him 'fish boy' to your father! Clearly you are not as obtuse as you are pretending to be right now."_  
  
**I can't be certain.**  
  
_"Well, do not fret. **I** am certain that if he is not your fish boy, he is close enough to be someone of importance. Now, turn around. He awaits the tunic. Be sure to touch his chest first."_ Sothis cannot help but tease her lightly. _"Try not to enjoy it too much."_  
  
Byleth sighs, turning around. As Sothis mentions, he is indeed standing, at last partially clothed. Byleth takes the tunic in hand. As he reaches for it, she stops him. "Wait, I... please trust me." He tilts his head inquisitively, so she takes a deep breath. "I..." She points to herself. "You..." She points to him. "Touch." She mimes pressing her hand against her chest. His eyes widen in comprehension, before he nods with some uncertainty. He folds his hands behind his back, grasping one wrist with the other as he waits.  
  
Reaching out, Byleth places her flat palm against his chest. And when she does--  
  
A rush of images fills her mind. An explosion, deep in a place that could only be the sea. Clashing armor and waves and then, Dedue washing ashore--_ah, so that is his name_\--and then, from his perspective, she sees her small self approaching him on the beach. More images flow into her mind. He's been looking for her because beneath the sea, because of war, his people are gone and there is another figure telling him to swim, swim to land and never return. She is the only person he knows above land and now after many years--  
  
She gasps, taking a step back. For once, Sothis has almost nothing to say. Almost. _"How exhausting... Please update me later... will... you?"_ Sothis falls silent, but it does not matter now. She has words to say to him.  
  
"You're him. The fish boy I saw on the beach." He looks conflicted for a moment at the word 'fish' before nodding in agreement. "And you don't have anyone else." He nods firmly again. Her voice is filled with a quiet marvel. "And you can understand me now." Another nod. She stares at him, then crosses her arms. "It's nice to finally meet you. My name is Byleth."  
  
"I... am Dedue." His eyes widen as he touches his own lips, then grimaces, apparently at the sound of his own voice. "What did you do?" Byleth shrugs, in part because she does not know the answer, in part because if she did, she would have to explain Sothis, and she does not know enough about him to do such a thing.  
  
"Welcome to Garreg Mach."  
  
He clears his throat. "Yes, I am aware. This is the haven of the goddess, is it not?"  
  
Byleth lifts an eyebrow. "You know of Sothis?"  
  
He shrugs. "I do not know her name in your tongue, but... we have stories. A creator who gave us form before leaving to bless the land. Some say she was to return but..." He trails off. Her questions come, flat and direct, at the end of each answer.  
  
"Did you know I was here?"  
  
He shakes his head. "I came for sanctuary, but... I could not reveal myself. For these few months, I have kept watch from beneath the pond. When I saw you, I... suspected."  
  
"How?"  
  
"Your earring." Byleth hand drift upwards to light on the fan shape hooked in her ear. "I gave it to a... someone I knew, many years ago." Sheepishly, he rubs his neck. "Actually, I did not mean to reveal myself now." At her inquisitive stare, Dedue clears his throat. "I... I merely wished to enter into the building with unseeable walls." He grimaces, but his response only peaks her curiosity.  
  
_The greenhouse? What could possibly be of interest there?_  
  
"You like... flowers from land?" He nods once in reply. "Why?" Dedue hesitates. Holding out his hand, she notices for the first time that his fist has been tightly clamped shut around... something. He opens it, and inside, there is a polished wooden flower blossom, wet and worn with age.  
  
It's a figurine that she should not recognize, and yet... she does. Actually, Byleth can see it in her minds' eye, sitting on a dirt floor as her father whittles away at the piece of wood she has carefully selected.  
  
_"Kid, you're really testing my abilities with these flower gifts."_ He grumbled the words under his breath, but... he'd kept carving.  
  
"They are such... beautiful things. I wish to learn to care for them, if I could. And... if possible... to make things such as this." He trails off, standing. "But I do not wish to bother you."  
  
Byleth stops him with a hand. "Allow me to bother you, would you?" Dedue looks at her inquisitively as she digs through a drawer. Finally she finds what she seeks--a small box filled to the brim with tiny scrolls. "This is the last one I received before we had to leave. What does it say?" Dedue looks surprised that she has kept them all of this time. He carefully peels open the one she offers, his eyes scanning the symbols that she has never been able to decipher. The further he reads, the lower his eyebrows tilt, until he finishes the scroll, his lips tilted low in a deep frown.

"It is... something I wrote five years ago." She... knows that as much. _Just 'something'? _She looks to him for more information but he avoids her gaze. The candlelight in her room is dim but in the glow of the fire she can almost swear that in spite of his displeased expression, Dedue's ears are red. "A poem I wrote for someone who's attentions I wished to catch." He stares down at her, then looks away. "But it has been many years, and I do not expect such things." Byleth finds herself wordless. Usually she does not wish to speak, but not... no words come to mind as he stares down at her with an unreadable expression in his light eyes. Byleth finds her words.

"The room beside mine is vacant." She will need to speak with Se--Rhea. Seteth will, most likely, say no the moment he realizes that Dedue's origins are more cast in shadow than even hers are. _Still..._ She thinks on her father's words.  
  
_A magnet for mystery... Someone who attracts all kinds of trouble._ He is right, of course. But...  
  
She looks at the man standing in her room, pulling the tunic over his head. Some forms of attraction, she thinks, should not be fought.

**Author's Note:**

> This particular fic is a request from [@SpooderHearts](https://twitter.com/SpooderHearts) who asked for Merman Dedue! I hope you like it and thank you for the challenge.
> 
> Happy Deduesday, guys!


End file.
